Retry transient Windows atomic write failures

[medisean]

Closes #2573

Summary:

• Retry transient PermissionError failures during Windows atomic replacement.
• Add regression coverage for a replacement that succeeds after retries.

Tests:

• Python syntax compilation passed.

[gemini-code-assist]

Code Review

This pull request introduces retry logic in LocalStorage._write_file to handle transient PermissionError exceptions during os.replace operations, which typically occur on Windows, and adds a corresponding unit test. The review feedback suggests restricting this retry behavior to Windows platforms (os.name == 'nt') to avoid unnecessary delays on non-Windows systems where such errors are usually permanent, and recommends mocking os.name in the unit test to ensure it passes across all platforms.

[gemini-code-assist]

On non-Windows platforms (like Linux/macOS), a PermissionError during os.replace is typically a permanent permission issue (e.g., write permission denied) rather than a transient sharing violation. Retrying in these cases introduces unnecessary delays (up to 100ms) before raising the exception.

We should restrict this retry behavior to Windows (os.name == 'nt').

Note: _write_json_file (line 553) also uses os.replace and could suffer from the same transient Windows failures. Consider extracting this retry logic into a shared helper function (e.g., _safe_replace) so both _write_file and _write_json_file can reuse it.

Suggested change

	except PermissionError:
	if attempt == 4:
	raise
	time.sleep(0.01 * (attempt + 1))
	except PermissionError:
	if os.name != "nt" or attempt == 4:
	raise
	time.sleep(0.01 * (attempt + 1))

[gemini-code-assist]

To ensure this test passes on non-Windows platforms (where os.name is not 'nt'), we should mock os.name to 'nt' using monkeypatch so that the retry logic is triggered and tested correctly.

Suggested change

	monkeypatch.setattr(os, "replace", replace_with_transient_lock)
	monkeypatch.setattr(os, "name", "nt")
	monkeypatch.setattr(os, "replace", replace_with_transient_lock)

[varungup90]

Can you sign the PR

[Copilot]

Pull request overview

Adds retries for transient Windows permission failures during atomic local-storage writes.

Changes:

• Retries os.replace up to five times with incremental delays.
• Adds regression coverage for a transient replacement failure.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
python/aibrix/aibrix/storage/local.py	Adds retry logic for payload replacement.
python/aibrix/tests/storage/test_local_storage.py	Tests successful replacement after one retry.

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